Microprocessor coupled with a digitally switched potentiometer

ABSTRACT

A microprocessor comprises a central processing unit with an execution unit for executing instructions. A memory unit is coupled with the central processing unit through a bus. Furthermore, a potentiometer sub-circuit is provided and a data transfer unit is coupled with the memory unit and the potentiometer sub-circuit, wherein the data transfer unit transfers data between the memory unit and the potentiometer sub-circuit upon execution of a predefined instruction.

FIELD OF THE INVENTION

[0001] The present application relates generally to microprocessors coupled with an electronic potentiometer such as a microcontroller and a method of operating such a microprocessor.

BACKGROUND OF THE INVENTION

[0002] Microcontrollers are used in many applications and comprise usually a plurality of peripheral components. Within a microcontroller a central processing unit (CPU) having a arithmetic logic unit (ALU) and a load and store unit or a combination of both is located. The CPU is coupled through a bus with a memory to provide storage capacity for program instructions and data. Program and data memory can be separate with different bus lines or embodied in a single memory unit. Other peripheral components may be coupled through the same or additional busses. A known peripheral device is a electronic potentiometer, for example a digitally switched potentiometer as disclosed in U.S. Pat. No. 6,201,491 which is hereby incorporated by reference. Such a digitally switched potentiometer can be controlled by the CPU and is therefore coupled through such a bus with the CPU. A microcontroller is designed to execute a plurality of instructions. The instruction set defines the capability of the respective microcontroller. The processing speed of a microcontroller depends on many factors. The instruction set is one of them as complex tasks might need a plurality of instructions to be executed. Generally one can say, the less number of instructions have to be executed for a specific task the faster that task can be performed. For supplying a digitally switched potentiometer with data, the CPU has to load that data into the registers and then move the data to the digitally switched potentiometer. A problem occurs in case a lot of data transfers have to be executed. In such a case significant time might be used to perform such a task.

SUMMARY OF THE INVENTION

[0003] Therefore, the present application discloses exemplary embodiments which overcome the above mentioned problems as well as other shortcomings and deficiencies of existing technologies.

[0004] In a first exemplary embodiment a microprocessor comprises a central processing unit with an execution unit for executing instructions. A memory unit is coupled with the central processing unit through a bus. Furthermore, a potentiometer sub-circuit is provided and a data transfer unit is coupled with the memory unit and the potentiometer sub-circuit, wherein the data transfer unit transfers data between the memory unit and the potentiometer sub-circuit upon execution of a predefined instruction.

[0005] A method of transferring data between a memory unit and a potentiometer sub-circuit within a microcontroller arrangement comprises the steps of:

[0006] providing an instruction set for the microcontroller wherein an instruction within said instruction set defines a data transfer between the memory unit and the potentiometer sub-circuit;

[0007] upon execution of the instruction transferring data between the memory unit and the potentiometer sub-circuit.

[0008] The data transfer unit of the microprocessor may comprise a counter having an clock input receiving a clock and an output which is coupled with the memory unit. Furthermore a programmable divider unit for dividing the clock may be provided. The data transfer unit may further comprise a loop register and an incrementer unit coupled with the loop register. The memory unit can be a EEPROM or a FLASH EEPROM.

[0009] The instruction may comprise an opcode and an address specifying a memory location or an opcode and an address specifying a start memory location and a end memory location. In another embodiment, the instruction comprises an opcode and an address specifying a start memory location and a number indicating the number of consecutive data from said start memory location.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more complete understanding of the present disclosure and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

[0011]FIG. 1 shows a block diagram of an exemplary embodiment of the present invention;

[0012]FIG. 2 shows a block diagram of another exemplary embodiment of the present invention;

[0013]FIG. 3 shows details of yet another exemplary embodiment of the present invention;

[0014]FIG. 4 shows an exemplary instruction structure according to an embodiment of the present invention; and

[0015]FIG. 5 shows a graph of a signal generated by an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Turning to the drawings, exemplary embodiments of the present application will now be described. In FIG. 1, some important elements of a microcontroller are shown in this exemplary embodiment according to the present invention. A central processing unit (CPU) 100 comprises an execution unit 101 for executing instructions provided, for example, by a memory unit 110 which is coupled with the CPU 100 through a bus. In this embodiment data and programs are stored commonly within a memory unit 110. Of course, programs can be stored separately within a special program memory area having its own program memory bus. Memory unit 110 comprises a memory section 111 which is a dedicated section of memory unit 110 for providing data to a digitally switched potentiometer 120. Therefore, digitally switched potentiometer sub-circuit 120 is coupled with this memory section 111. Memory section 111 in this embodiment comprises, for example, 256 memory cells starting from 00h to FFh. Again, memory section 111 can also be a separate independent memory unit coupled with a separate or a peripheral bus. The digitally switched potentiometer sub-circuit 120 comprises a control register 121 whose content controls the wiper position of the potentiometer.

[0017] According to the exemplary embodiment of the present invention the instruction set comprises two specific defined instructions for data transfer between the potentiometer sub-circuit 121 and the memory section 111. A first instruction, for example, addresses the memory section 111 with an offset value. FIG. 4 shows an exemplary structure of such an instruction. The first portion 400 of the instruction contains the opcode identifying the instruction, for example A4h, and the second portion 410 contains the offset value, for example 22h. This instruction initiates a move of the content from memory location 22h to the control register 121 within digitally switched potentiometer sub-circuit 120. In this example, the memory section 111 within memory unit 110 starts at location 00h. Of course, any other address is possible. 255 memory cells follow consecutively from this first memory cell up to location FFh. Any other number of cells is possible. The offset value allows to reach any memory location within memory section 111. Execution of this instruction can be performed within a single cycle, thus allowing quick transfers from memory unit 110 to digitally switched potentiometer sub-circuit 120. The second instruction can perform a reverse function in which the content of control register 121 is transferred to a specified location within memory section 111. Central processing unit 100 comprises all necessary components to initiate the data transfer. Respective control signals are sent to memory unit 110 and digitally switched potentiometer sub-circuit 120 through respective data and control lines.

[0018]FIG. 2 depicts another embodiment according to the present invention. Again, CPU 100 comprises an execution unit which is coupled with an eight bit counter 200. Counter 200 receives a counter clock signal from the output of a divider 210 whose input receives a clock signal 220. Divider 210 is programmable by CPU 100. The output of counter 200 addresses memory unit 240 which again comprises 256 memory cells in form of an EEPROM or equivalent volatile or non-volatile memory. Memory unit 240 is coupled through a data bus with digitally switched potentiometer sub-circuit 120 which again comprises a control register 121. The data transfer is initiated by respective control signals generated from the counter clock signal as indicated in FIG. 2. In this embodiment a separate program memory 250 is provided which supplies CPU 100 with instructions through a dedicated bus.

[0019] This embodiment can provide additional functionality, for example, if combined with the above described embodiment. A dedicated instruction can start a process in which a plurality of values is permanently transferred to digitally switched potentiometer sub-circuit 120 in a loop mode. To this end, execution unit 101 resets counter 200 and controls divider 210 to generate a counter clock output signal. This signal is used to generate control signals to transfer the output of counter 200 as an address to memory unit 240. The data value from the addressed memory cell within memory unit 240 is then transferred into control register 121 of digitally switched potentiometer sub-circuit 120. Counter 200 is then incremented and the above described steps are repeated. As counter 200 is an eight bit counter 256 consecutive addresses are generated and output to memory unit 240. Once counter reaches the value FFh=256 the next clock resets the counter value to 00h=0 and the procedure is repeated. Thus, a loop mode is initiated. This way, repetitive signals can be generated. Divider 210 provides the feature of different sampling clocks. Divider 210 is programmable and can therefore provide a plurality of different counter clock signals. Different instructions can be defined to operate this embodiment. For example, an instruction can setup a counter clock speed, another instruction can start the counter and yet another can stop the counter.

[0020]FIG. 3 depicts yet another embodiment of a loop feature as described in FIG. 2. Instead of a counter a register 300 is coupled with an incrementer 310. Furthermore, a compare and reset unit is provided which is connected to register 300. The output signal 330 of register 300 is again used to address a memory unit containing a plurality of consecutive values to be transmitted to a digitally switched potentiometer sub-circuit 120.

[0021] This embodiment comprises even greater flexibility as a plurality of sections within a memory unit can be addressed and used for a loop function. Compare and reset unit can be programmed to store a start value and an end value. Initially, compare and reset unit 320 transfer the start value into register 300. Incrementer 310 can be triggered by a divider as shown in FIG. 2. Thus consecutive addresses are output at output 330 of register 300. Compare and reset unit 320 compares the content of register 320 with the end value. Once the end value is reached in register 300, compare and reset unit 320 transfer the start value into register 300. Thus, a very flexible loop mechanism can be provided.

[0022]FIG. 5 shows an output signal which can be generated by any embodiment of the present invention. The specific form of a output signal is digitized and stored within memory locations 00h to FFh. According to the first embodiment a program loop body contains the dedicated instruction to transfer data from memory section 111 to digitally switched potentiometer sub-circuit 120. Furthermore, the address value is incremented within the loop. According to the second and third embodiment divider 210 is programmed to generate a respective counter clock signal and upon execution of a dedicated instruction the values of memory section 240 are consecutively transferred to digitally switched potentiometer sub-circuit 120. Thus an output signal as shown in FIG. 5 can be generated with no further processing by CPU 100.

[0023] The invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While the invention has been depicted, described, and is defined by reference to exemplary embodiments of the invention, such references do not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alternation, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts and having the benefit of this disclosure. The depicted and described embodiments of the invention are exemplary only, and are not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects. 

What is claimed is:
 1. A microprocessor comprising: a central processing unit comprising an execution unit for executing instructions; a memory unit coupled with said central processing unit through a bus; a potentiometer sub-circuit; a data transfer unit coupled with said memory unit and said potentiometer sub-circuit, wherein said data transfer unit transfers data between said memory unit and said potentiometer sub-circuit upon execution of a predefined instruction.
 2. Microprocessor according to claim 1, wherein said data transfer unit comprises a counter having an clock input receiving a clock and an output which is coupled with said memory unit.
 3. Microprocessor according to claim 2, further comprising a programmable divider unit for dividing said clock.
 4. Microprocessor according to claim 1, wherein said data transfer unit comprises a loop register and an incrementer unit coupled with said loop register.
 5. Microprocessor according to claim 1, wherein said memory unit is a EEPROM.
 6. Microprocessor according to claim 1, wherein said memory unit is a FLASH EEPROM.
 7. Microprocessor according to claim 1, wherein said instruction comprises an opcode and an address specifying a memory location.
 8. Microprocessor according to claim 2, wherein said instruction comprises an opcode and an address specifying a start memory location and an address specifying an end memory location.
 9. Microprocessor according to claim 4, wherein said instruction comprises an opcode and an address specifying a start memory location and a number indicating the number of consecutive data from said start memory location.
 10. Method of transferring data between a memory unit and a potentiometer sub-circuit within a microcontroller arrangement comprising: providing an instruction set for said microcontroller wherein an instruction within said instruction set defines a data transfer between said memory unit and said potentiometer sub-circuit; upon execution of said instruction transferring data between said memory unit and said potentiometer sub-circuit.
 11. Method according to claim 10; wherein said instruction includes an opcode and an address, said address determining a memory transfer location within said memory unit.
 12. Method according to claim 10, further comprising: defining a loop instruction upon execution of which a start location and end location within said memory unit are defined and the content of said defined loop is transferred stepwise to said potentiometer sub-circuit.
 13. Method according to claim 10, wherein said instruction initiates a transfer from said memory unit to said potentiometer sub-circuit.
 14. Method according to claim 10, wherein said instruction initiates a transfer from said potentiometer sub-circuit to said memory unit.
 15. Method according to claim 12, wherein upon execution of said loop instruction a counter is started, whereby said counter addresses said memory unit.
 16. Method according to claim 12, wherein said instruction comprises an opcode and an address specifying a start memory location and an address specifying an end memory location.
 17. Method according to claim 12, wherein said instruction comprises an opcode and an address specifying a start memory location and a number indicating the number of consecutive data within from said start memory location. 